Optical output device and optical output method

Abstract

An optical output device (2) that, before a signal light pulse (21) is inputted to an input end (31) of an optical waveguide (3) having a nonlinear optical effect, inputs a first pump light pulse (11) to the input end (31), and after the first pump light pulse (11) is inputted to the input end (31), inputs a second pump light pulse (12) to the input end (31), and after the signal light pulse (21) and the second pump light pulse (12) are inputted to the input end (31), inputs a third pump light pulse (13) to the input end (31). The first pump light pulse (11), the second pump light pulse (12), and the third pump light pulse (13) have the same group velocity in the optical waveguide (3). The first pump light pulse (11) and the signal light pulse (21) have different group velocities in the optical waveguide (3). The intensities of the first pump light pulse (11), the second pump light pulse (12), and the third pump light pulse (13) are greater than the intensity of the signal light pulse (21). The intensities of the first pump light pulse (11) and the third pump light pulse (13) are greater than or equal to the minimum intensity when the signal light pulse (21) is totally reflected in the optical waveguide (3). The intensity of the second pump light pulse (12) is less than the minimum intensity.

Description

Optical output device and optical output method

[0001] The present invention relates to a light output device and a light output method.

[0002] Optical circuits based on optical interferometers are considered important as hardware for next-generation information processing technologies that use light, such as optical quantum computers, optical AI accelerators, and spatial multiplexing transmission communications. By combining a large number of optical interferometers, optical circuits can be realized on an optical table or on a silicon wafer.

[0003] The scale of information processing is limited by the space available for realizing optical circuits. Large-scale optical circuits are necessary for large-scale information processing. Therefore, there is a need to reduce the area of ​​optical circuits and perform larger-scale information processing in a limited space. To reduce the area of ​​optical circuits, there is a need to realize optical interferometers in small spaces.

[0004] Optical interferometers are comprised of optical elements such as beam splitters and mirrors. For example, beam splitters use dielectric multilayer films deposited on glass or other substrates. Their basic operating principle is the reflection and refraction of light at the boundary between media with different refractive indices (dielectric constants). Naturally, such refractive index boundaries are spatially formed. Recently, the possibility of creating a temporal refractive index boundary, in which the refractive index of a medium changes at a certain time, has been explored. It has been shown that a temporal refractive index boundary can be realized by the optical Kerr effect (cross-phase modulation), a type of nonlinear optical effect in optical fibers (e.g., Non-Patent Documents 1 and 2). The possibility of realizing a Fabry-Perot interferometer using two pump beams to realize a total-reflection mirror using such a temporal refractive index boundary has been suggested (e.g., Non-Patent Document 3).

[0005] BW Plansinis et al., Phys. Rev. Lett., vol. 115, 183901 (2015).BW Plansinis et al., Journal of the Optical Society of America B, Vol. 35, No. 2, 436 (2018).J. Zhang et al., Journal of the Optical Society of America B, Vol. 38, No. 8, 2376 (2021).J. Carolan et al., Science, Vol. 349, No. 6249, 711 (2015).N. Matsuda, Science Advances, vol. 2, e1501223, (2016).

[0006] On the other hand, there have been no reports of the realization of a Mach-Zehnder interferometer, which is important in optical circuits. However, the optical circuits for application to next-generation information processing technology mentioned in the background art are constructed using a Mach-Zehnder interferometer (e.g., Non-Patent Document 4). Therefore, in order to realize optical circuits for next-generation information processing technology using a space-time refractive index boundary, it is important to have a method for realizing a Mach-Zehnder interferometer. However, no method for realizing a Mach-Zehnder interferometer using a space-time refractive index boundary has been reported. An object of the present invention is to provide an optical output device and an optical output method that realize an optical interferometer in a small space.

[0007] One aspect of the present invention is an optical output device that inputs a first pump optical pulse to an input end of an optical waveguide having a nonlinear optical effect before a signal optical pulse is input to the input end, inputs a second pump optical pulse to the input end after the first pump optical pulse is input to the input end, and inputs a third pump optical pulse to the input end after the signal optical pulse and the second pump optical pulse are input to the input end, wherein the group velocities of the first pump optical pulse, the second pump optical pulse, and the third pump optical pulse are the same and the group velocities of the first pump optical pulse and the signal optical pulse are different, the intensities of the first pump optical pulse, the second pump optical pulse, and the third pump optical pulse are greater than the intensity of the signal optical pulse, the intensities of the first pump optical pulse and the third pump optical pulse are equal to or greater than the minimum intensity when the signal optical pulse is totally reflected, and the intensity of the second pump optical pulse is less than the minimum intensity.

[0008] One aspect of the present invention is an optical output method comprising: inputting a first pump optical pulse to an input end of an optical waveguide having a nonlinear optical effect before a signal optical pulse is input to the input end; inputting a second pump optical pulse to the input end after the first pump optical pulse is input to the input end; and inputting a third pump optical pulse to the input end after the signal optical pulse and the second pump optical pulse are input to the input end; wherein the group velocities of the first pump optical pulse, the second pump optical pulse, and the third pump optical pulse are the same, and the group velocities of the first pump optical pulse and the signal optical pulse are different, the intensities of the first pump optical pulse, the second pump optical pulse, and the third pump optical pulse are greater than the intensity of the signal optical pulse, the intensities of the first pump optical pulse and the third pump optical pulse are equal to or greater than a minimum intensity when the signal optical pulse is totally reflected, and the intensity of the second pump optical pulse is less than the minimum intensity.

[0009] According to the present invention, a Mach-Zehnder type optical interferometer can be realized in a small space.

[0010] Fig. 1 is a diagram showing a configuration of an optical interferometer according to the present embodiment; Fig. 2 is a diagram showing an example of a first pump light pulse, a second pump light pulse, a third pump light pulse, and a signal light pulse input to an optical waveguide; Fig. 3 is a diagram showing propagation of a signal light pulse; Fig. 4 is a diagram showing an example of a first pump light pulse, a second pump light pulse, a third pump light pulse, and a signal light pulse input to an optical waveguide; Fig. 4 is a diagram showing propagation of a signal light pulse; Fig. 5 is a diagram showing simulation results.

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a diagram showing the configuration of an optical interferometer 1 according to this embodiment. The optical interferometer 1 is a device that splits a signal light pulse into two beams of light, recombines the beams, and causes them to interfere with each other. The optical interferometer 1 includes an optical output device 2 and an optical waveguide 3.

[0012] The optical output device 2 outputs a signal optical pulse to the input end 31 of the optical waveguide 3. The optical output device 2 outputs an optical pulse (pump optical pulse) different from the signal optical pulse to the input end 31 of the optical waveguide 3. The wavelength of the signal optical pulse and the wavelength of the pump optical pulse are different. The signal optical pulse and the pump optical pulse propagate through the optical waveguide 3. The optical output device 2 is, for example, a pulse laser. The optical waveguide 3 has a nonlinear optical effect, for example, an optical fiber. The optical waveguide 3 has an input end 31 and an output end 32. The signal optical pulse and the pump optical pulse input to the input end 31 from the optical output device 2 propagate through the optical waveguide 3 and are output from the output end 32. The output end 32 has two output ports that are spatially identical but output at different times. The output ports are connected to a detector or the input end of an optical interferometer similar to the optical interferometer, and when combined, form an optical circuit.

[0013] A temporal refractive index boundary is induced by the optical Kerr effect (or cross-phase modulation) occurring between the signal optical pulse and the pump optical pulse propagating through the optical waveguide 3. The optical Kerr effect is a type of nonlinear optical effect, a phenomenon in which the refractive index changes depending on the optical intensity. The induction of a temporal refractive index boundary by the optical Kerr effect is disclosed, for example, in Non-Patent Documents 1 and 2. When a temporal refractive index boundary is induced, the signal optical pulse is totally reflected by the pump optical pulse, or is partially reflected and partially transmitted, if certain conditions are met. This causes the optical interferometer 1 to interfere with the signal optical pulse. Detailed characteristics of the pump optical pulse for interfering the signal optical pulse will be described later. It is desirable that the pump optical pulse satisfy the soliton propagation conditions for propagating through the optical waveguide 3 without changing its shape. Furthermore, since the optical Kerr effect occurring between the signal optical pulse and the pump optical pulse occurs reciprocally, the nonlinear effect from the signal optical pulse to the pump optical pulse also appears. Therefore, it is desirable that the ratio of the intensity of the signal light pulse to that of the pump light pulse be small so that the influence of the nonlinear effect from the signal light pulse to the pump light pulse is small.

[0014] The device for outputting signal light pulses may be provided separately from light output device 2. When the device for outputting signal light pulses is provided separately from light output device 2, light output device 2 does not output signal light pulses.

[0015] The signal light pulse and the pump light pulse propagate through the optical waveguide 3 and are output from the output end 32 of the optical waveguide 3. By using a wavelength filter, it is possible to extract only the interfered signal light pulse from the output end 32 of the optical waveguide 3. Furthermore, the length of the optical waveguide 3 may be set according to the propagation distance of the signal light pulse and the pump light pulse.

[0016] The optical output device 2 outputs three pump optical pulses, a first pump optical pulse 11, a second pump optical pulse 12, and a third pump optical pulse 13, to the input end 31 of the optical waveguide 3. The optical output device 2 outputs the first pump optical pulse 11 to the input end 31 of the optical waveguide 3 before outputting the signal optical pulse 21 to the input end 31 of the optical waveguide 3. After outputting the first pump optical pulse 11 to the input end 31 of the optical waveguide 3, the optical output device 2 outputs the second pump optical pulse 12 to the input end 31 of the optical waveguide 3. After outputting the signal optical pulse 21 and the second pump optical pulse 12 to the input end 31 of the optical waveguide 3, the optical output device 2 outputs the third pump optical pulse 13 to the input end 31 of the optical waveguide 3. The intensities of the first pump optical pulse 11, the second pump optical pulse 12, and the third pump optical pulse 13 are greater than the intensity of the signal optical pulse 21. The intensities of the first pump light pulse 11 and the third pump light pulse 13 are equal to or greater than the minimum intensity required for total reflection of the signal light pulse 21. The conditions for the first pump light pulse 11 and the third pump light pulse 13 for total reflection of the signal light pulse 21 will be described later. The intensity of the second pump light pulse 12 is equal to or less than the minimum intensity required for total reflection of the signal light pulse 21, and is determined by the branching ratio of the signal light pulse 21. The conditions for the second pump light pulse 12 for branching the signal light pulse 21 will be described later.

[0017] The group velocities of the first pump light pulse 11, the second pump light pulse 12, and the third pump light pulse 13 are the same. The group velocities of the pump light pulses 11 to 13 are different from the group velocity of the signal light pulse 21. The difference in group velocities between the pump light pulses 11 to 13 and the signal light pulse 21 can be realized by group velocity dispersion of the optical waveguide 3. The signal light pulse 21 is totally reflected due to the optical Kerr effect between the first pump light pulse 11 and the third pump light pulse 13. The signal light pulse 21 is partially transmitted and partially reflected due to the optical Kerr effect between the second pump light pulse 12 and the signal light pulse 21.

[0018] The timings at which the first pump light pulse 11, the second pump light pulse 12, the third pump light pulse 13, and the signal light pulse 21 are output, the group velocities of the pump light pulses 11 to 13, and the group velocity of the signal light pulse 21 are desirably set so that the signal light pulse 21 approaches the second pump light pulse 12 earlier than the first pump light pulse 11 and the third pump light pulse 13. This allows the signal light pulse 21 to be branched by the second pump light pulse 12 before being totally reflected by the first pump light pulse 11 or the third pump light pulse 13.

[0019] 2 is a diagram showing an example of a first pump light pulse 11, a second pump light pulse 12, a third pump light pulse 13, and a signal light pulse 21 input to an input end 31 of an optical waveguide 3. The optical output device 2 inputs the pump light pulses 11 to 13 and the signal light pulse 21 to the input end 31 of the optical waveguide 3 in the order of the first pump light pulse 11, the second pump light pulse 12, the signal light pulse 21, and the third pump light pulse 13. The group velocities of the pump light pulses 11 to 13 are smaller than the group velocity of the signal light pulse 21.

[0020] 3 is a diagram showing the propagation of the signal light pulse 21. Because the group velocity of the signal light pulse 21 is greater than that of the second pump light pulse 12, the signal light pulse 21 and the second pump light pulse 12 approach each other, and due to the optical Kerr effect, the signal light pulse 21 is split into a first signal light pulse 21-1 that transmits through the second pump light pulse 12 and propagates at a positive speed relative to the first pump light pulse 11, and a second signal light pulse 21-2 that is reflected by the second pump light pulse 12 and propagates at a negative speed relative to the first pump light pulse 11. The second pump light pulse 12 performs an operation equivalent to that of a beam splitter.

[0021] The first signal light pulse 21-1 approaches the first pump light pulse 11. The first signal light pulse 21-1 is totally reflected due to the optical Kerr effect. The second signal light pulse 21-2 approaches the third pump light pulse 13. The second signal light pulse 21-2 is totally reflected due to the optical Kerr effect. The first pump light pulse 11 and the third pump light pulse 13 act like mirrors. The totally reflected first signal light pulse 21-1 and second signal light pulse 21-2 both approach the second pump light pulse 12 again and are each split into two optical pulses. The first signal light pulse 21-1 is split into a transmitted first signal light pulse 21-1-1 that is transmitted by the second pump light pulse 12 and propagates at a negative speed relative to the first pump light pulse 11, and a reflected first signal light pulse 21-1-2 that is reflected by the second pump light pulse 12 and propagates at a positive speed relative to the first pump light pulse 11. The second signal light pulse 21-2 is branched into a transmitted second signal light pulse 21-2-1 that transmits through the second pump light pulse 12 and propagates at a positive velocity relative to the first pump light pulse 11, and a reflected second signal light pulse 21-2-2 that is reflected by the second pump light pulse 12 and propagates at a negative velocity relative to the first pump light pulse 11. Thereafter, the transmitted first signal light pulse 21-1-1 and the reflected second signal light pulse 21-2-2 interfere with each other. Furthermore, the reflected first signal light pulse 21-1-2 and the transmitted second signal light pulse 21-2-1 interfere with each other.

[0022] By changing the timing at which the pump light pulses 11 to 13 are output, the light output device 2 can change the length of the optical path through which the first signal light pulse 21-1 and the second signal light pulse 21-2 pass, thereby changing the phase difference between the first signal light pulse 21-1 and the second signal light pulse 21-2. The change in the phase difference thus generated changes the intensity of light generated by interference between the transmitted first signal light pulse 21-1-1 and the reflected second signal light pulse 21-2-2, and the intensity of light generated by interference between the reflected first signal light pulse 21-1-2 and the transmitted second signal light pulse 21-2-1. Changing the timing at which the pump light pulses 11 to 13 are output corresponds to changing the length between the beam splitter and the mirror or changing the refractive index of the medium through which light propagates in a typical optical interferometer.

[0023] The time t from when the first pump light pulse 11 is input until when the second pump light pulse 12 is input １２ and / or the time t from when the second pump light pulse 12 is input until when the third pump light pulse 13 is input. ２３ is preferably adjusted within a range in which the first signal light pulse 21-1 and the second signal light pulse 21-2 overlap in time. This allows the transmitted first signal light pulse 21-1-1 and the reflected second signal light pulse 21-2-2 to overlap in time sufficiently. The same applies to the reflected first signal light pulse 21-1-2 and the transmitted second signal light pulse 21-2-1.

[0024] 4 is a diagram showing an example of a first pump light pulse 11, a second pump light pulse 12, a third pump light pulse 13, and a signal light pulse 21 input to an input end 31 of the optical waveguide 3. The optical output device 2 outputs the pump light pulses 11 to 13 and the signal light pulse 21 to the input end 31 of the optical waveguide 3 in the order of the first pump light pulse 11, the signal light pulse 21, the second pump light pulse 12, and the third pump light pulse 13. The group velocity of the pump light pulses 11 to 13 is greater than the group velocity of the signal light pulse 21.

[0025] 5 is a diagram showing the propagation of the signal light pulse 21. Because the group velocity of the signal light pulse 21 is smaller than that of the first pump light pulse 11, the signal light pulse 21 and the second pump light pulse 12 approach each other, and the signal light pulse 21 is totally reflected by the optical Kerr effect. Thereafter, the signal light pulse 21 and the second pump light pulse 12 approach each other, and the signal light pulse 21 is split by the optical Kerr effect into a first signal light pulse 21-1 that transmits through the second pump light pulse 12 and propagates at a negative velocity relative to the first pump light pulse 11, and a second signal light pulse 21-2 that is reflected by the second pump light pulse 12 and propagates at a positive velocity relative to the first pump light pulse 11.

[0026] The first signal light pulse 21-1 approaches the third pump light pulse 13. The first signal light pulse 21-1 is totally reflected due to the optical Kerr effect. The second signal light pulse 21-2 approaches the first pump light pulse 11. The second signal light pulse 21-2 is totally reflected due to the optical Kerr effect. The totally reflected first signal light pulse 21-1 and second signal light pulse 21-2 both approach the second pump light pulse 12 again and are each branched into two optical pulses. The first signal light pulse 21-1 is branched into a transmitted first signal light pulse 21-1-1 that transmits through the second pump light pulse 12 and propagates at a positive speed relative to the first pump light pulse 11, and a reflected first signal light pulse 21-1-2 that is reflected by the second pump light pulse 12 and propagates at a negative speed relative to the first pump light pulse 11. The second signal light pulse 21-2 is branched into a transmitted second signal light pulse 21-2-1 that transmits through the second pump light pulse 12 and propagates at a negative velocity relative to the first pump light pulse 11, and a reflected second signal light pulse 21-2-2 that is reflected by the second pump light pulse 12 and propagates at a positive velocity relative to the first pump light pulse 11. Thereafter, the transmitted first signal light pulse 21-1-1 and the reflected second signal light pulse 21-2-2 interfere with each other. Furthermore, the reflected first signal light pulse 21-1-2 and the transmitted second signal light pulse 21-2-1 interfere with each other.

[0027] By adjusting the timing at which the first pump light pulse 11, the second pump light pulse 12, and the third pump light pulse 13 are output from the light output device 2, it is possible to adjust the phase difference that is acquired within the optical waveguide 3 between the time when the first signal light pulse 21-1 and the second signal light pulse 21-2 are split once by the beam splitter based on the second pump light pulse 12 and the time when they are combined again by the beam splitter based on the second pump light pulse 12.

[0028] The following describes the conditions for the first pump light pulse 11 and the third pump light pulse 13. Because the conditions for the first pump light pulse 11 and the third pump light pulse 13 are the same, only the first pump light pulse 11 will be described. The first pump light pulse 11 and the signal light pulse 21 satisfy formula (1).

[0029] In formula (1), β ２is the group velocity dispersion of the light having the wavelength of the signal light pulse 21 in the optical waveguide 3. Ｂ = k ０ Δn. k ０ is the wave number in vacuum of the wavelength of the signal light pulse 21. ０ is expressed as k using the wavelength λ of the signal light pulse 21. ０ = 2π / λ. Δn is the change in refractive index of the optical waveguide 3 in the signal light pulse 21 induced by the first pump light pulse 11. Δβ １ is the difference in group velocity between the first pump light pulse 11 and the signal light pulse 21. The third pump light pulse 13 and the signal light pulse 21 similarly satisfy equation (1). The minimum value of the intensity of the pump light pulse when equation (1) is satisfied is the minimum intensity when the pump light pulse totally reflects the signal light pulse 21. The refractive index change Δn is a value determined by equation (2).

[0030] In equation (2), γ is the nonlinear constant of the optical waveguide 3, and is a value representing the magnitude of the nonlinear optical effect that the first pump light pulse 11 exerts on the signal light pulse 21. P(t) is the optical intensity of the first pump light pulse 11, and is the square of the envelope of the electric field of the first pump light pulse 11.

[0031] The second pump light pulse 12 and the signal light pulse 21 do not satisfy formula (1). The branching ratio between the first signal light pulse 21-1 and the second signal light pulse 21-2 is determined by solving the coupled nonlinear Schrodinger equation. The coupled nonlinear Schrodinger equation is expressed by formulas (3) and (4).

[0032] In equations (3) and (4), A is the envelope of the electric field of the optical pulse, p is the pump optical pulse, and s is the signal optical pulse. A is a function of the propagation distance z and T, where T is T = t - z / v ｇ and is a time referenced to the center of the second pump light pulse 12. Here, v ｇ is the group velocity of the pump light pulse. In equations (3) and (4), β ｐ（ｓ），ｋ is the k-th order propagation constant of the optical waveguide 3. ｐis a nonlinear constant that represents the magnitude of the nonlinear optical effect that the pump light pulses 11 to 13 exert on themselves in the optical waveguide 3. ｐｓ is a nonlinear constant representing the magnitude of the nonlinear optical effect that the pump light pulses 11 to 13 have on the signal light pulse 21 in the optical waveguide 3. By solving equations (3) and (4) under the condition that the intensities of the first signal light pulse 21-1 and the second signal light pulse 21-2 after branching are the same, the intensity of the second pump light pulse 12 when the intensity ratio of the first signal light pulse 21-1 to the second signal light pulse 21-2 is 1:1 can be calculated.

[0033] Note that equations (3) and (4) are examples of coupled nonlinear Schrödinger equations, and coupled nonlinear Schrödinger equations expressed in different ways may be used. The condition under which the signal light pulse 21 is totally reflected by the first pump light pulse 11 and the third pump light pulse 13 may also be calculated by solving the coupled nonlinear Schrödinger equations.

[0034] (Simulation Results) The simulation results will be explained below. The conditions for the first pump light pulse 11, the second pump light pulse 12, and the third pump light pulse 13 are as follows: 2 The pulse shape was a .times. ...

[0035] Nonlinear constant γ ｐ is 11 / W / km, and the group velocity dispersion β of the pump light pulses 11 to 13 in the optical waveguide 3 ｐ,２ is -0.061 ps ２The peak intensity P that satisfies the soliton propagation condition in which the pump light pulses 11 to 13 propagate through the optical waveguide 3 without changing their shape is expressed by equation (5).

[0036] Therefore, the peak intensities of the first pump light pulse 11, the second pump light pulse 12, and the third pump light pulse 13 were adjusted to be near the values ​​expressed by equation (5).

[0037] The conditions for the signal light pulse 21 are as follows: 2 The pulse shape was a .beta.-type pulse, with a full width at half maximum of 1.5 ps and a wavelength of 0.75 μm. The pulse peak intensity was set to a value of 0.1 W or less. If the pulse peak intensity is a value less than 0.1 W, the influence of the nonlinear effect from the signal light pulse 21 on the pump light pulses 11 to 13 can be sufficiently reduced. The time of incidence into the optical waveguide 3 was −2.0 ps, ​​with the second pump light pulse 12 as the reference. The group velocity of the signal light pulse 21 was greater than the group velocity of the pump light pulses 11 to 13, and the magnitude of the differential group delay with respect to the pump light pulses 11 to 13, |Δβ １ |=|β ｐ,１ -β ｓ,１ The nonlinear constant γ ｐｓ is 7.2 / W / km, and the group velocity dispersion β ｓ,２ is +0.036ps ２ / m. A simulation was performed in advance to solve the coupled nonlinear Schrodinger equation between the signal light pulse 21 and the second pump light pulse 12, and the intensity of the second pump light pulse 12 was adjusted so that the signal light pulse 21 would be branched into the first signal light pulse 21-1 and the second signal light pulse 21-2 at an intensity branching ratio of 1:1. In this simulation, a parameter related to the optical waveguide 3 (nonlinear constant γ ｐ , γ ｐｓ , group velocity dispersion β ｐ，２ , β ｓ，２ , differential group delay, and other attenuation constants α and higher-order propagation constants not explicitly stated here) are parameters of an actual optical fiber. This optical fiber is mentioned in Non-Patent Document 5.

[0038] 5 shows the results of the simulation. The graph shown in FIG. 5 shows the intensities of the signal light pulse 21, the branched first signal light pulse 21-1, and the second signal light pulse 21-2, with the vertical axis representing the distance z from the incident position of the optical pulse on the optical waveguide 3 and the horizontal axis representing the time T relative to the second pump light pulse 12. The time at which the first pump light pulse 11 was incident was set to five times: +4.91 ps, +4.95 ps, +4.98 ps, +5.01 ps, and +5.05 ps. By changing the incident time of the first pump light pulse 11, different interferences occurred when the branched first signal light pulse 21-1 and second signal light pulse 21-2 were multiplexed. For example, when the incidence time of the first pump light pulse 11 is +4.91 ps, the combined signal light pulse 21 has a stronger intensity of light with a group velocity larger than that of the pump light pulses 11 to 13, whereas when the incidence time of the first pump light pulse 11 is +5.05 ps, the combined signal light pulse 21 has a stronger intensity of light with a group velocity smaller than that of the pump light pulses 11 to 13. This is because the incidence time of the first pump light pulse 11 is changed to change the phase difference between the first signal light pulse 21-1 and the second signal light pulse 21-2. In this way, by changing the propagation distance of the two signal light beams and changing the phase difference between the two beams, it is possible to confirm the operation of the optical interferometer 1, in which the branching ratio of the light output from the two output ports of the optical waveguide 3 is switched.

[0039] According to this embodiment, the optical output device 2 and the optical waveguide 3 can perform the same operation as a Mach-Zehnder interferometer. The optical interferometer 1 of this embodiment can reduce the space it occupies by using, for example, an optical fiber as the optical waveguide 3. This makes it possible to realize an optical interferometer in a small space.

[0040] Other Embodiments One embodiment of the present invention has been described in detail above with reference to the drawings, but the specific configuration is not limited to that described above, and various design changes and the like can be made within the scope that does not deviate from the gist of the present invention.

[0041] 1 Optical interferometer, 2 Optical output device, 3 Optical waveguide, 11 First pump optical pulse, 12 Second pump optical pulse, 13 Third pump optical pulse, 21 Signal optical pulse, 21-1 First signal optical pulse, 21-1-1 Transmitted first signal optical pulse, 21-1-2 Reflected first signal optical pulse, 21-2 Second signal optical pulse, 21-2-1 Transmitted second signal optical pulse, 21-2-2 Reflected second signal optical pulse

Claims

1. An optical output device which inputs a first pump optical pulse to an input end of an optical waveguide having a nonlinear optical effect before a signal optical pulse is input to the input end, inputs a second pump optical pulse to the input end after the first pump optical pulse is input to the input end, and inputs a third pump optical pulse to the input end after the signal optical pulse and the second pump optical pulse are input to the input end, wherein the group velocities of the first pump optical pulse, the second pump optical pulse and the third pump optical pulse in the optical waveguide are the same, and the group velocities of the first pump optical pulse and the signal optical pulse are different in the optical waveguide, the intensities of the first pump optical pulse, the second pump optical pulse and the third pump optical pulse are greater than the intensity of the signal optical pulse, the intensities of the first pump optical pulse and the third pump optical pulse are equal to or greater than the minimum intensity when the signal optical pulse is totally reflected in the optical waveguide, and the intensity of the second pump optical pulse is less than the minimum intensity.

2. The optical output device of claim 1, wherein the first pump light pulse, the second pump light pulse, the signal light pulse, and the third pump light pulse are input to the input end in that order, or the first pump light pulse, the signal light pulse, the second pump light pulse, and the third pump light pulse are input to the input end in that order, and the group velocity of each pulse is set so that the signal light pulse approaches the second pump light pulse before the first pump light pulse and the third pump light pulse.

3. The light output device of claim 1, wherein a time from when the first pump light pulse is input to when the second pump light pulse is input and / or a time from when the second pump light pulse is input to when the third pump light pulse is input is adjusted within a range in which a first signal light pulse, which transmits through the second pump light pulse, propagates at a positive speed relative to the first pump light pulse and is totally reflected by the first pump light pulse, and a second signal light pulse, which is reflected by the second pump light pulse, propagates at a negative speed relative to the first pump light pulse and is totally reflected by the third pump light pulse, overlap in time, or a first signal light pulse, which transmits through the second pump light pulse, propagates at a negative speed relative to the first pump light pulse and is totally reflected by the third pump light pulse, and a second signal light pulse, which is reflected by the second pump light pulse, propagates at a positive speed relative to the first pump light pulse and is totally reflected by the first pump light pulse, overlap in time.

4. The optical output device according to any one of claims 1 to 3, wherein the intensity of the second pump light pulse is determined by calculating a coupled nonlinear Schrodinger equation in the optical waveguide between the signal light pulse and the second pump light pulse.

5. The optical output device according to claim 4, wherein the intensity of said second pump light pulse is an intensity when said signal light pulse is split in said optical waveguide into first signal light and second signal light having an intensity ratio of 1:

1.

6. A method of optical output comprising: inputting a first pump optical pulse to an input end of an optical waveguide having a nonlinear optical effect before a signal optical pulse is input to the input end; inputting a second pump optical pulse to the input end after the first pump optical pulse has been input to the input end; and inputting a third pump optical pulse to the input end after the signal optical pulse and the second pump optical pulse have been input to the input end, wherein the group velocities of the first pump optical pulse, the second pump optical pulse and the third pump optical pulse in the optical waveguide are the same and the group velocities of the first pump optical pulse and the signal optical pulse are different in the optical waveguide; intensities of the first pump optical pulse, the second pump optical pulse and the third pump optical pulse are greater than that of the signal optical pulse; intensities of the first pump optical pulse and the third pump optical pulse are equal to or greater than a minimum intensity when the signal optical pulse is totally reflected in the optical waveguide, and an intensity of the second pump optical pulse is less than the minimum intensity.